Hay — Further Observations on Some Extinct Elephants. 99 



of plates. I grant that Osborn's type, his paratypes (his figs. 

 11, 12), and various other specimens have only 7 or 8 plates in 

 100 mm. and that they are co-specific with his E. jeffersonii, 

 my E. boreus. Inasmuch as teeth of the forms that I have been 

 referring to E. columbi and E. primigenius have typically 24 

 plates in 100 mm. it follows that if teeth of both forms have the 

 same length there will be the same number of plates in 100 mm. 

 The teeth of E. columbi are usually the larger, but sometimes 

 those of E. boreus (hitherto referred to E. primigenius) attain 

 equal size, as in the case of Osborn's paratypes from Zanesville, 

 Ohio. Nevertheless, there are usually differences in the thick- 

 ness and the complications of the enamel, in the shape of the 

 plates, often strongly bent in E. columbi, and in the outlines of 

 the tooth. 



Under his Elephas jeffersonii Osborn (his p. 15) has included, 

 besides the type skull and the Cincinnati skull, two others in the 

 American Museum. These are a skull from Whitman County, 

 Washington, and another from Dallas, Texas. He states that 

 the cranial characters of the Cincinnati skull are wholly similar 

 to those of the three skulls in the American Museum, and he 

 calls attention to the differences existing between these "rela- 

 tively long, broad, and shallow crania and the relatively short, 

 narrow, and deep crania of E. primigenius. " 



In my paper of June 12 I have from careful measurements 

 constructed diagrams of a skull from Siberia (figs. 1, 2), of the 

 Dallas skull (figs. 3, 4), of the Cincinnati skull (figs. 5, 6), and 

 of the Whitman County skull (figs. 9, 10). I believe that these 

 diagrams give correct views of the architecture of these crania. 

 The skull taken as type of E. jeffersonii (diagram not pubHshed) 

 is essentially the same as that of E. boreus. The differences 

 between these and E. primigenius ( = E. mammonteus) noted by 

 Osborn are in general correctly stated; and these characters 

 taken in connection with the swollen occiput of E. boreus justify 

 the separation of the American form. On the other hand, the 

 skull of E. boreus is wholly different from the Whitman County 

 skull. Measured by the unit I have used for the length, this 

 cranium is much wider and much higher than either E. mammon- 

 teus or E. boreus. In the latter the height is hardly one percent 

 greater than the length; in E. mammonteus the height is 12 per- 

 cent greater; in the Whitman County skull, 28 percent greater. 



